X-ray diffraction study of some liquid naphthalene derivatives

The structure of the liquids 1-Methylnaphthalene C10H7-CH3 and 1-Chloronaphthalene C10H7-Cl was investigated using X-ray diffraction at 293 K. Monochromatic radiation MoKalpha (lambda = 0.7107 Angstrom) enabled determination of the scattered radiation intensity between S-o = 4 pi sin theta (0)/lambda = 0.430 Angstrom (-1) and S-max = 14.311 Angstrom (-1). Angular distributions of X-ray scattered intensity were measured, and differential radial distribution functions of electron density (DRDFs) were calculated. The mean distances between the neighbouring molecules and the ranges of the spheres of intermolecular ordering were found. X-ray structural analysis was applied for determination of the packing coefficient of molecules of the liquids studied. A simple model of short-range arrangement of the molecules was proposed, which seems to be valid for other weakly polar monosubstituted naphthalene derivatives in the liquid phase.